The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A fuel control system controls provision of fuel to an engine. The fuel control system includes an inner control loop and an outer control loop. The inner control loop may use data from an exhaust gas oxygen (EGO) sensor located upstream from a catalyst in an exhaust system. The catalyst receives exhaust gas output by the engine.
The inner control loop controls the amount of fuel provided to the engine based on the data from the upstream EGO sensor. For example only, when the upstream EGO sensor indicates that the exhaust gas is (fuel) rich, the inner control loop may decrease the amount of fuel provided to the engine. Conversely, the inner control loop may increase the amount of fuel provided to the engine when the exhaust gas is lean. Adjusting the amount of fuel provided to the engine based on the data from the upstream EGO sensor modulates the air/fuel mixture combusted within the engine at approximately a desired air/fuel mixture (e.g., a stoichiometry mixture).
The outer control loop may use data from an EGO sensor located downstream from the catalyst. For example only, the outer control loop may use the response of the upstream and downstream EGO sensors to determine an amount of oxygen stored by the catalyst and other suitable parameters. The outer control loop may also use the response of the downstream EGO sensor to correct the response of the upstream and/or downstream EGO sensors when the downstream EGO sensor provides an unexpected response.